1. Field of the Invention
The present invention relates to an apparatus and a method for performing a recording operation by ejecting ink to a medium to be recorded.
2. Description of the Prior Art
To perform a printing operation by employing an ink jet recording process, an ink which contains water soluble pigment, water soluble solvent and water as main components is usually used from the viewpoint of safety, easy handling and color conditioning. However, when the foregoing kind of water based ink is used for recording operations each performed using a so-called ordinary paper such as a high quantity paper, a copying papers or the like as a recording papers (recording media to be recorded with ink), there arises an occasion that the following several problems appear in the course of each recording operation.
Firstly, since ordinary papers each serving as a recording paper have comparatively poor ink permeability, a long time is required for achieving a step of fixing. For this reason, there arise problems that a recorded image is contaminated with unfixed ink due to contact with a certain unit placed on a transport path, a user's hand is contaminated with it, other recording paper is contaminated with it, and a recording unit is contaminated with it.
Secondly, when a color recording operation is performed, there arises an occasion that different kinds of colors are mixed with each other on a recording paper for the reason of poor ink permeability. In this case, a clear image can not be recorded on the recording paper.
Thirdly, when an ink readily permeable into ordinary papers is used in order to avoid the aforementioned problems, there arises an occasion that a coloring substance in the ink excessively permeates into the recording paper. In this case, so-called ink penetration occurs or good color development is not achieved with the recording paper after completion of a recording operation.
To obviate these problems, several proposals have been made with respect to a recording process as disclosed in, e.g., Japanese Patent Application Laying-Open Nos. 60-107975 and 3-231861. The recording process proposed according to each of prior arts is practiced such that a certain image is not recorded on a recording paper at a time but it is recorded on the recording paper by dividing the certain image into two parts per each pixel and then recording them at each of two scanning operations. Consequently, a quantity of ink to be permeated into the recording paper can relatively be reduced. Thus, even in case that recording papers each having poor ink permeability are used for recording operations, there does not arise the problem that different kinds of color inks are mixed with each other on a recording paper because they quickly permeate into the recording paper. Since a quantity of ink to be injected at a time can be reduced to a half when the proposed recording process is employed, there does not arise the problem that coloring substance excessively permeates into the recording paper even when an ink readily permeable into the recording paper is used for a recording operation. Consequently, a clear image visually recognizable with a beautiful color can easily be obtained with the proposed recording process.
However, in case that a recording operation is performed using a recording paper having more poor ink permeability or in case that a quantity of ink to be ejected per unit area is increased in order to raise up an image density for a clear image, it is practically difficult to solve the aforementioned problems with the proposed recording process. Specifically, since each recording operation is achieved by twice scanning divided images with the proposed recording process, a time interval between two scanning operations is relatively shortened in case that each recording operation is performed using a recording paper having poor ink permeability or in case that a quantity of ink to be ejected is increased. Further, since a subsequent droplet of ink is ejected to the recording paper before a droplet of ink ejected for a preceding recording operation is sufficiently fixed, there arises an occasion that the aforementioned three problems appear.